-LRB- CNN -RRB- -- Peanut butter makers not affected by the deadly salmonella outbreak linked to a Georgia peanut plant are trying to get consumers to keep buying peanut butter . It could be an uphill battle .

J.M. Smucker Co. wants to assure consumers that its Jif brand of peanut butter is safe to eat .

Companies such as ConAgra Foods Inc. and J.M. Smucker Co. have started running ads and offering coupons , trying to lure peanut butter customers as sales have plunged at least 20 percent since the salmonella outbreak .

Eight people have died and nearly 600 have been sickened in the outbreak . The original peanut butter recall launched weeks ago has expanded to include more than 1,000 products .

On ConAgra 's Web site , a letter assures customers that the company 's peanut butter is safe .

`` ConAgra Foods , the maker of Peter Pan Peanut Butter , has confirmed that none of the ingredients used to make Peter Pan Peanut Butter come from Peanut Corporation of America , the company linked to the government 's current salmonella investigation , '' the letter says . `` We are extremely confident in the safety protocols . ''

J.M. Smucker , maker of Jif peanut butter , had a similar message for customers .

`` Our Smucker 's peanut butter brand and peanut butter products are safe for consumption . The J.M. Smucker Company does not purchase peanuts or any ingredients from Peanut Corporation of America , '' its Web site says .

The Peanut Corporation of America is under investigation by the Food and Drug Administration , and the FBI searched its Blakely , Georgia , plant on Monday , CNN affiliate WALB-TV in Albany , Georgia , reported .

Americans have shied away from peanut butter despite the FDA 's assurances that major-label peanut butter in grocery stores is safe . Watch a senator express outrage at the outbreak ''

`` With eight dead and almost 600 sick , it 's a time to be prudent , '' said Dr. Douglas Powell , an associate professor of food safety at Kansas State University , which is the home of the International Food Safety Network .

There 's another problem , Powell said : `` None of these companies are really coming out and saying this is what we do to ensure safety . They say , ` Yeah , we test for salmonella . ' But are those tests public ? They 're not . ''

Shoppers are wary because they do n't know which products are safe , he said .

Tainted peanut butter and peanut paste were shipped by Peanut Corporation of America to institutions such as schools , nursing homes and prisons , not to grocery stores . But that is n't preventing consumers from playing it safe .

Powell said he understands .

`` If you 're a parent packing a lunch and you have all the hectic things going on in the morning , is it really realistic to say , hey , before you put that peanut snack cracker individually wrapped item into your kid 's lunch , you 're going to go onto the Internet and check a Web site ? I think that 's a bit much . I think it 's prudent to avoid this stuff until we see where this is going , '' he said .

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Makers of Peter Pan and Jif distance firms from salmonella contamination

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Companies assure public they do n't use products from suspect plant

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Retail peanut butter sales have dropped 20 percent since salmonella outbreak